1. Field of the Invention
The present invention relates to a laminated structure, a donor substrate and a fabrication method for a laminated structure, such as a micro optical part, a micro mechanical part and a micro fluidic device, and a metallic mold for forming them, obtained by laminating patterns formed by electroforming.
2. Description of the Related Art
A lamination modeling method is being rapidly spread in recent years as a method of forming a three-dimensional part having a complex shape designed with a computer in a short delivery period. A three-dimensional part fabricated by the lamination modeling method is utilized as a model of a part (prototype) of various equipments for investigating quality of performance and shape of the part. The size of the part, to which the method is applied, has been relatively large as being several centimeters or larger, but there is such a demand that the method is applied to production of a micro structure, such as a micro optical part and a micro mechanical part, formed through high-precision processing.
As a fabrication process of a microstructure, for example, the following process has been known. A low-adhesion layer of polyimide or a thermal oxide film and an conductive layer are formed sequentially on a Si wafer substrate, and a resist pattern layer with a reversal pattern of a cross sectional pattern is formed on the conductive layer. A cross sectional pattern part is formed by plating in the space of the resist pattern layer, and the resist, pattern layer is removed to fabricate a donor substrate. A target substrate is disposed to face the donor substrate, and such an operation is repeated that the target substrate aligned to the cross sectional pattern part is contacted thereto under pressure and then released therefrom, whereby the cross sectional pattern part is transferred and laminated onto the target substrate to construct a laminated structure (See, for example, JP-A-2004-358602 ([0027] - [0035], FIGS. 1 to 6.)
According to the conventional process for producing a laminated structure, however, the donor substrate is produced by the electroforming method, which brings about a problem inherent to the electroforming method, i.e., a poor thickness profile is obtained. The poor thickness profile appears as such a phenomenon as a slanted electroformed surface, an increased thickness of the film near the resist, a dome-like electroformed surface, and fluctuation in thickness of the film caused by fluctuation in density of distances in the resist pattern. Accordingly, it is difficult to fabricate a laminated structure with good accuracy and good yield.
An object of the invention is to provide such a laminated structure, a donor substrate and a process for producing a laminated structure that a laminated structure can be fabricated with good accuracy and good yield even in the case where fluctuation occurs in thickness of the electroconductive film formed by electroforming.